Many current and past motorized handpieces have been used by dental professionals to rotate a file or other cutting instrument and to simultaneously supply an irrigating liquid, such as in the form of a water jet, to rinse the repair site during the cutting operation. These instruments are especially useful during root canal procedures. The water jet commences upon activation of the handpiece motor and, therefore, commences simultaneously with rotation of the cutting tool.
Unfortunately, the simultaneous activation of the motor and initiation of the irrigating liquid causes the liquid to strike the rotating cutting tool before the tip of the cutting tool can be located at the repair site, such as within the root canal of a tooth. The resulting spray makes it difficult to see the repair site, such as the root canal opening, and this, in turn, makes insertion of the rotating cutting tool into the root canal potentially more error prone. Also, the user typically clamps the file within the jaws of the instrument by briefly activating the motor with the tip located outside the patient's mouth. This leads to an undesirable spray of liquid outside the patient's mouth as well.
For the foregoing reasons, and to solve various problems in this area, it would be desirable to provide a rotary dental instrument and methods which allow the dental professional to present the cutting tool at the repair site prior to an automatic initiation of the irrigating liquid.